JPH05319605A - Automatic paper feeding device and image reader - Google Patents

Abstract

PURPOSE:To reduce failure in paper-separating and paper-conveying and to enhance the durability of an automatic paper feeding device by making the hardness of a reversing roller equal to or lower than that of a separating roller together with making the width of the reversing roller narrower than that of the separating roller, thereby eliminating the formation of unbalanced wear in the reverse roller or of a dent in the separating roller. CONSTITUTION:A device disclosed in this invention is provided with a sheet supporting means 34, on which a sheet 36 is mounted, a separating roller 30, which is driven in the direction in which the sheet 36 is conveyed, and a reversing roller 1, which abuts on the separating roller 30 and which is driven opposite to the direction in which the sheet 36 is conveyed. In this case, the hardness of the reversing roller 1 is made equal to or lower than that of the separating roller 30, while the width of the reversing roller 1 is made narrower than that of the separating roller 30. In addition, it is preferable to make the friction coefficient of the reversing roller 1 to the sheet 36 equal to or lower than that of the separating roller 30 to the sheet 36. For example, the reversing roller 1 is made of silicone rubber having the hardness of 30 deg., while the separating roller 30 is made of EPDM whose rubber hardness is 40 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse roller type automatic paper feeder with a torque limiter (hereinafter referred to as a reverse roller ADF with a torque limiter) that separates and feeds originals and recording sheets of a facsimile, a copying machine, a printer, etc. one by one. That said).

2. Description of the Related Art Conventionally, an ADF of a type that separates and feeds a plurality of sheets one by one by controlling the forward rotation / reverse rotation / stop of the reverse rotation roller by cooperation of a separation roller, a reverse rotation roller, and a torque limiter is widely known. There is. Further, in this method, the width of the reverse rotation roller is equal to the width of the separation roller.

[0003]

However, in the above-mentioned conventional example, even if the widths of the reversing roller and the separating roller are made equal, they are not actually equal due to manufacturing variations (variation within dimensional tolerance), or the widths of both rollers are not equal. Since they come into contact with each other while being displaced in the direction, there are the following drawbacks.

In the reverse rotation roller ADF, the reverse rotation roller wears with an increase in the number of sheets passed, but the amount of this wear is large at the contact portion (the portion where contact pressure is applied) with the separation roller,
Since there is little or almost no wear in the non-contact portion, the reverse rotation roller R is unevenly worn and a step is formed between the reverse rotation roller R and the separation roller S as shown in FIG. As a result, separation failure (non-feeding, double feeding) may occur or streaks may be formed on the sheet at the step.

If the hardness of the reverse rotation roller R (rubber) is increased in order to reduce the wear of the reverse rotation roller, FIG.
As shown in (3), the separation roller S is dented, which also causes separation failure and streaks on the sheet.

[0006]

In order to solve the above problems, in the present invention, the hardness of the reversing roller is equal to or lower than the hardness of the separating roller, and the width of the reversing roller is set to be smaller than that of the separating roller. I made it narrower than the width.

Since the width of the reversing roller is narrower, even if the positions of both rollers in the width direction are displaced and come into contact with each other, the entire width of the reversing roller is included inside the entire width of the separating roller, so that the reversing roller is unevenly worn. Furthermore, since the hardness of the reverse rotation roller is not higher than that of the separation roller, the separation roller is not dented.

Further, if the material of the reversing roller is selected and the coefficient of friction for the sheet is equal to or lower than the coefficient of friction for the sheet of the separating roller, it is in a standby state when many sheets are placed and conveyed. It is possible to prevent the trouble that the sheet is jammed before the nip formed by the reverse roller and the separation roller and is not fed.

Generally, the lower the hardness of rubber is, the higher the friction coefficient becomes. Therefore, "the material is selected so that the hardness of the reverse roller is made equal to or less than the hardness of the separating roller so that the friction coefficient does not become high". Need to be careful. Otherwise, the friction coefficient of the reversing roller will be high, and the frictional load will increase, leading to problems such as non-feeding and poor conveyance speed.

The simplest and surest way to realize this hardness relationship is to use the same material for the reversing roller and the separating roller.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a case where the present invention is applied to a facsimile machine, and a portion where a sheet original is fed to an image reading section x is extracted, and FIG. 2 is a perspective view taken along the line AA of FIG. 3 is a main part view of FIG. 1 as viewed in B, and FIG. 4 is a main part view of FIG. 1 as viewed in C.

In these drawings, 1 is a reverse roller, 2 is a reverse roller shaft, 3 is a pinch roller, 4 is a pinch roller shaft, 5 is a reverse roller holder for holding the reverse roller shaft 2 through a bearing, and 6 is a bearing. A pinch roller holder for holding the pinch roller shaft 4, a frame 7, a support shaft 8 for rotatably holding the reverse rotation roller holder 5, the pinch roller holder 6, and the frame 7, 9, 10, 11, 1
Gears 2 and 13 transmit the drive from the pinch roller shaft 4 to the reverse rotation roller shaft 2 with 16 teeth, 33 teeth, 22 teeth, respectively.
It has 47 teeth-29 teeth and 27 teeth.

Reference numeral 14 is a torque limiter, 15 is a rotation support shaft of the gear 12, 16 is a reverse roller spring for urging the reverse roller 1 via the reverse roller holder 5, and 17a and 17b are pinch roller 3 via the pinch roller holder 6. Pinch roller springs 18a, 18b, 18c for restricting the rotation of the reverse rotation roller holder 5 and the pinch roller holder 6 and 19 mounted on the frame 7 by means of screws 20a, 20b via a roller shaft 27. Rollers 26a, 26b,
26c is a leaf spring for urging.

The above units 1 to 20 constitute an independent unit (hereinafter referred to as a reverse rotation roller unit), and the screws 21
Upper document guide 22 by a, 21b, 21c and 21d
Attached to.

Further, 23a and 23b are guides made of a low-rigidity member disposed on the left and right of the reverse rotation roller 1, 24 is a pressure contact arm, and 25 is a pressure contact arm spring for urging the pressure contact arm against the pre-conveying roller 28. One unit (hereinafter, referred to as an upper document guide unit) is configured with the reverse rotation roller units 1 to 27 attached to the upper document guide 22.

Reference numeral 29 is a pre-conveying roller shaft for rotatably supporting the pre-conveying roller 28, 30 is a separating roller, 31 is a separating roller shaft, 32 is a feeding roller, 33 is a feeding roller shaft, and 34 is a lower original guide which is a sheet table. Is. Further, the upper document guide unit is a fulcrum 3 provided on a part of the upper document guide 22.
It is rotatably supported by a main body frame (not shown) of the facsimile apparatus by 5a and 35b, and is held at a constant height with respect to the lower document guide, 34 by a locking means (not shown).

When the locking means (not shown) is released, the upper original guide unit can be lifted as shown in FIG. Conversely, if the upper document guide unit is lowered and the locking means (not shown) is locked, the reverse rotation roller 1,
The pinch roller 3 comes into contact with the separation roller 30 and the feeding roller 32, respectively, and constitutes a reverse rotation roller type ADF. Reference numeral 36 is a sheet document.

The separating roller 30 and the feeding roller 32 are driven in the direction of the arrow in FIG. 2 by a driving source (not shown). Further, the torque limiter 14 is set to slip when a load torque equal to or greater than a set value TR set in the reverse rotation roller 1 is applied.

Further, the frictional force between the rollers or between the rollers and the sheet is applied between the reverse roller 1 and the separation roller 30 ... F1 Between the pinch roller 3 and the feeding roller 32 ... F2 Between the reverse roller 1 and the sheet 36 ... F3 Between the separation roller 30 and the sheet 36 ... F4 Between the two sheets 36 ... ..F5 Between pinch roller 3 and sheet 36 ..... F6 Between feeding roller 32 and sheet 36 ..... F7, and the radii of the reverse roller 1 and pinch roller 3 are r1. , R2 and the reduction ratio of the gear train from the pinch roller 3 to the reverse rotation roller 1 is η, the friction coefficient of each roller and the reverse rotation roller spring 16 and the pinch roller springs 17 a, 1
Depending on 7b, the above-mentioned values are F1r1> TR ... (i) F3r1>TR> F5r1 ... (ii) F4> F5 ... (iii) ηF2r2> TR ... (iv) ηF6r2> TR. (V) Since ηF7r2> TR ... (Vi) is set, the reverse rotation roller type ADF with the torque limiter operates as follows according to the setting of the sheet original 36 on the lower original guide 34. ..

(1) In the case of no sheet In the cases (i) and (iv), the reverse rotation roller 1 and the pinch roller 3 rotate together with the separation roller 30 and the feeding roller 32, and the torque limiter 14 slips.

(2) When there is one sheet (ii) (F3r1> TR), (v) (vi)
The reverse rotation roller 1 and the pinch roller 3 rotate together with the separation roller 30 and the feeding roller 32 via the sheet, and the torque limiter 14 slips (performs the same operation as (1)).

(3) When the number of sheets is two or more: (ii), (iii), (v), and (vi), the pinch roller 3 rotates together with the feeding roller 32 through the sheet and the reverse rotation roller. 1 reverses and returns the sheets other than the lowest sheet upstream in the sheet conveying direction. The torque limiter 14 does not slip.

When the number of sheets is two or more in (3), the reverse rotation roller 1 reversely rotates to return the sheets other than the lowest one.
After that, the reverse rotation roller stops when the sheets other than the lowest sheet have been completely returned.

As shown in FIG. 7, this is the frictional force F3 'between the sheet 36 and the reverse rotation roller 1, and the frictional force F5' generated against the reverse rotation roller 1 by the friction of the waiting sheet 37 with the sheet 36. This is because the torque (F3 ′ + F5 ′) r1 generated by the resultant force (F′3 + F5 ′) with the balance with the torque TR biased to the reverse rotation roller 1 (F3 ′).
Is smaller than F3 when there is no standby sheet 37. This is because the standby sheet 37 reduces the contact area with the reverse rotation roller 1.

If the standby sheet 37 bites further downstream than in the state of FIG. 7, F3 'becomes smaller and (F3' + F5 ') r1 <TR, so that the reverse roller 1
Reversely returns the seat 37, and if the seat 37 is excessively returned, F3 'becomes large this time, and (F3' +
F5 ') r1> TR, so reverse roller 1 is sheet 3
6 (37), the sheet 37 advances in the downstream direction.
There is a point where the forces are balanced between these two states, and the reverse rotation roller 1 is stopped).

The circumferential surface of the stopped reverse rotation roller 1 is rubbed against the sheet 36 being conveyed and worn. If you repeat the sheet conveyance many times, the points of wear will change, so
Eventually, it will wear out all around.

Now, suppose that the reverse roller has a lower hardness than the separating roller and has the same width. Even though the widths are the same, in reality, due to variations in manufacturing of individual parts and rattling in assembling, both rollers hardly match with each other, and some deviation occurs. Then, due to the pressure, the contacting part is greatly worn,
The parts that are not in contact with each other hardly wear.

As a result, as the number of sheets passed increases, FIG.
As described above, the reverse rotation roller wears unevenly and causes separation failure.

On the other hand, when the reverse rotation roller has a higher hardness, as shown in FIG. 12, a dent is formed on the separation roller side, causing separation failure and damaging the original.

However, in this embodiment according to the present invention, the reverse roller and the separating roller are made of the same material so that the hardness is the same, and the width of the reverse roller is larger than the width of the separating roller as shown in FIG. Since it is made narrow, the reverse rotation roller is not unevenly worn and the separation roller is not dented. Also in this embodiment, the reversing roller is worn, but since it occurs uniformly over the entire width of the reversing roller, troubles such as defective separation do not occur, and the durability of the apparatus is significantly improved.

In this embodiment, since the reverse roller 1 and the separating roller 30 are made of the same kind of silicone rubber, the fluctuation of F1 is small and the condition (i) is controlled.
Further, since F3 = F4, both the conditions (ii) and (iii) can be easily managed.

Further, the silicone rubber has a characteristic that the friction coefficient is less deteriorated with respect to the silicone oil adhering to the copy paper or the like, and the effect that the copy paper or the like to which the silicone oil adheres can be stably fed. is there.

Further, even a curled sheet can be fed by the guides 23a and 23b without turning the leading edge. Further, since the reverse rotation roller 1 is driven from the pinch roller 3 and the structure thereof is independent as the reverse rotation roller unit, the upper document guide unit can be released easily as described above, and the simple mechanism reduces the manufacturing cost and the failure rate. It is low and the exchangeability of the unit is good.

The configuration of the image reading section x in this embodiment is, as shown in FIG. 1, a light source 51, a reflecting mirror 52,
53, a lens 54, a photoelectric conversion element 55 such as a CCD, and the like.

(Other Embodiments) In the above embodiment, the reverse rotation roller 1 and the separation roller 30 are made of the same material, but the reverse rotation roller 1 is made of silicon having a rubber hardness of 30 °, for example.
The separation roller 30 may be made of EPDM having a rubber hardness of 40 °.

In the case of the same type of rubber, the lower the hardness is, the higher the friction coefficient is generally. However, by changing the type, the reverse rotation roller 1 has a low hardness (soft) but the friction coefficient is the same as that of the separation roller 30. It can be: This combination of silicone and EPDM utilizes the property that the friction coefficient of silicone rubber is lower than that of EPDM.

The friction coefficient of the reverse roller 1 is the separation roller 30.
The reason why it is preferable to be no more than that is to prevent a non-feeding trouble due to "leading edge clogging" of sheets when a large number of sheets are placed on a sheet table and fed.

The "leading edge" of a large number of sheets means that the placed sheets are sandwiched in front of the nip formed by the reverse rotation roller 1 and the separation roller 30, and the rotation of the reverse rotation roller 1 is stopped. It is a phenomenon.

This will be described with reference to FIG. 8. The frictional force F1 'received by the reverse rotation roller 1 from the separation roller 30 and the sheet bundle 38.
The frictional force F5 ″ received from the torque TR biased to the reverse rotation roller 1 and (F1 ′ + F5 ″) r1 = TR
Are balanced like.

At this time, the reverse rotation roller 1 receives a force of f in the direction in which the pressing force on the separation roller 30 is reduced by the sheet bundle 38, and the frictional force F1 'received from the separation roller 30 is separated when the sheet bundle 38 is not present. It is smaller than the frictional force F1 received from the roller 30.

The sheet bundle is referred to here as
A large number of placed sheets are sandwiched in front of the nip formed by the reverse rotation roller 1 and the separation roller 30, so that the pressure contact force between the sheets at the leading end portions of the sheets becomes large (reaction of f), and friction between sheets is generated. This is because the strength is increased and it behaves like a lump. This tendency becomes stronger as the surface of the sheet becomes rougher and the environment becomes more humid.

By the way, is it possible to feed out the lowest sheet in this "clogging the leading edge" state? Figure 9
In consideration of the balance of the forces acting on the lowermost sheet 36, the force is F = (F4−F3) + (F4′−F5 ″) + Fp, with the feeding direction being positive. Here, Fp is a conveyance force by a preliminary conveyance roller (not shown) that is provided upstream of the separation roller 30 and comes into contact with the lowest sheet and is fed in the downstream direction. Further, F4 'is a conveying force by the separation roller generated at the position of "clipped tip".

It is immediately apparent that F4'-F5 ''> 0 (the friction coefficient of the separating roller with respect to the sheet is greater than the friction coefficient of the sheets), and Fp> 0. Then, if F4-F3>, then F is positive and the lowest sheet is successfully fed out. However, in the present invention, the friction coefficient of the reverse roller 1 is made equal to or less than the friction coefficient of the separation roller 30. Therefore, F4-F3> 0 holds.

Particularly in the second embodiment, F4-F3> 0
Therefore, the power to be delivered is increased and the performance is more stable.

Even if F4−F3 <0, if the total of F is positive, it should be delivered, but in reality, the balance of force is delicate and the performance is not stable, which is not preferable.

[0046]

As described above, the hardness of the reversing roller is equal to or lower than the hardness of the separating roller, and the width of the reversing roller is narrower than the width of the separating roller. Since the separation roller cannot be dented, there is an effect that a separation / conveyance failure is unlikely to occur, the durability of the apparatus is improved, and the conveyed sheet is not damaged.

[Brief description of drawings]

FIG. 1 is a plan view of an automatic paper feeding unit of a facsimile apparatus embodying the present invention,

FIG. 2 is a perspective view taken along the line AA of FIG.

3 is a main part view of FIG.

FIG. 4 is a main part view of FIG.

FIG. 5 is a diagram showing a state in which an upper document guide unit is lifted,

FIG. 6 is a diagram showing a contact state between a reverse rotation roller and a separation roller according to the present invention;

FIG. 7 is a diagram of a state of force during separation and conveyance of a sheet,

FIG. 8 is an explanatory view of a tip, that is, a phenomenon,

FIG. 9 is a diagram showing a state of a force applied to the lowest sheet during separation and conveyance of a large number of sheets,

FIG. 10 is a diagram showing a case where the hardness of the reverse rotation roller is lower than that of the separation roller in the conventional example,

FIG. 11 is a view showing a case where the reverse rotation roller has a higher hardness than the separation roller in the conventional example,

[Explanation of symbols]

 1 Reverse rotation roller 14 Torque limiter 30 Separation roller

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04N 1/00 108 Q 7046-5C

Claims (3)

[Claims] 1. A sheet supporting means for placing a sheet, a separation roller driven in a sheet feeding direction, and a reverse roller abutting the separation roller and driven in a direction opposite to the sheet feeding direction. The automatic paper feeding device is characterized in that the reverse rotation roller has a hardness equal to or lower than the hardness of the separation roller, and the width of the reverse rotation roller is narrower than the width of the separation roller. 2. The automatic sheet feeding device according to claim 1, wherein the friction coefficient of the reverse rotation roller against the sheet is equal to or lower than the friction coefficient of the separation roller against the sheet. 3. A sheet supporting means for placing a sheet, a separation roller driven in a sheet feeding direction, and a reverse roller abutting the separation roller and driven in a direction opposite to the sheet feeding direction. A reading unit that reads an image of a sheet separated one by one by the separation roller and the reverse rotation roller, the hardness of the reverse rotation roller being equal to or lower than the hardness of the separation roller, and An image reading apparatus characterized in that the width of the reverse rotation roller is narrower than the width of the separation roller.